Linkage analysis with an interbreed backcross maps Dalmatian hyperuricosuria to CFA03.

Dalmatians, like humans, excrete uric acid in their urine. All other dogs and most mammals excrete allantoin, a water-soluble compound that is further along the purine degradation pathway. Excretion of uric acid at high concentrations (hyperuricosuria) predisposes Dalmatians to the formation of urinary urate calculi. Hyperuricosuria (huu) is found in all Dalmatians tested and is inherited as an autosomal recessive trait. A genome scan and linkage analysis performed on a Dalmatian x Pointer interbreed backcross detected a single linked marker, REN153P03, located on CFA03. Haplotype analysis of the region around this marker defined a 3.3-Mb interval flanked by single recombination events. This interval, which contains the huu mutation, is estimated to include 24 genes.